P-wave tomography beneath Greenland

The Tenth Symposium on Polar Science/Ordinary sessions: [OG] Polar Geosciences, Wed. 4 Dec. / 3F Seminar room, National Institute of Polar Researc

Characteristic atmosphere-ocean-solid earth interactions in the Antarctic coastal and marine environment inferred from seismic and infrasound recording at Syowa Station, East Antarctica

International audienceSeveral characteristic waves detected by seismographs in Antarctic stations have been recognized as originating from the physical interaction between the solid earth and the atmosphere-ocean-cryosphere system surrounding the Antarctic and may be used as a proxy for characterizing ocean wave climate. A Chaparral-type infrasound sensor was installed at Syowa Station (SYO; 39.6E, 69.0S), East Antarctica, in April 2008 during the International Polar Year (IPY2007-2008). Matching data are also available for this time period from the existing broadband seismic recorder located close by. Continuous infrasound data for 2008-2009 include background signals (microbaroms) with a broad peak in the wave period between the values of 4 and 10 s. Signals with the same period are recorded by the broadband seismograph at SYO (microseisms). This period band is identified as double-frequency microseisms/baroms (DFM). The DFM have relatively lower amplitudes during winter. We suggest that this is due to the sea-ice extent around the coast causing a decreased ocean loading effect. In contrast, the single frequency microseisms/baroms with a peak in period between 12 and 30 s are observed under storm conditions, particularly in winter. On the infrasound data, stationary signals are identified with harmonic overtones at a few Hertz to lowermost human audible band, which we suggest is due to local effects such as sea-ice cracking and vibration. Microseism measurements are a useful proxy for characterizing ocean wave climate, complementing other oceanographic and geophysical data. At SYO, continuous monitoring by both broadband seismograph and infrasound contributes to the Federation of Digital Seismographic Networks, the Comprehensive Nuclear-Test-Ban Treaty in the high southern latitudes and the Pan-Antarctic Observations System under the Scientific Committee on Antarctic Research

Interpretation of observed seismograms at the Arctic region using global seismic waveform modeling

第2回極域科学シンポジウム　共通セッション「大気-海洋-雪氷-固体地球の相互作用」 11月15日（火） 統計数理研究所 3階セミナー室

Influence of Antarctic ice sheet on observed seismograms at intra-Antarctic region

第2回極域科学シンポジウム/第31回極域地学シンポジウム 11月16日（水） 国立国語研究

Japanese contribution to the GreenLand Ice Sheet monitoring Network (GLISN)

第3回極域科学シンポジウム/特別セッション「これからの北極研究」11月28日（水） 国立極地研究所 2階大会議

Ambient noise cross-correlation analysis using broadband continuous seismic waveform data from the Greenland ice sheet

第6回極域科学シンポジウム[OG] 地圏11月16日（月）　国立極地研究所３階セミナー

コウタイイキ ジシン カンソクモウ (GLISN) ニヨル グリーンランド ヒョウショウ モニタリング

グリーンランド氷床は地球規模の気候変動に伴って融解が進行している.近年,氷床融解の過程で末端部の氷河が移動する際に,「氷河地震」と呼ばれる地震動が発生することが知られるようになり,地震観測による氷床モニタリングに関心が集まっている.2009 年に発足した「グリーンランド氷床の地震モニタリング観測網(GLISN)」は,氷床モニタリングを目的として国際共同でグリーンランドや周辺の島々に広帯域地震計を展開するプロジェクトである.日本はGLISN 発足時からの参加国として,2011 年から観測隊を派遣しており,米国と共同で氷床上に観測点1 点を新設したほか,他の観測点のメンテナンスにも従事している.これらの観測点から得られた長周期地震波形データは,全球地震波伝播モデリングによる理論波形との比較でチェックを行い,設置場所によるノイズの影響が少ない,良質なデータであることを確認した.Global climate change is currently causing melting of the Greenland ice sheet. Recently, a new type of seismic event, referred to as a "glacial earthquake", has been recognized. Such earthquakes are generated by the movements of large masses of ice within the terminal regions of glacier, and represent a new approach for monitoring ice sheet dynamics. In 2009, the multinational GreenLand Ice Sheet monitoring Network (GLISN), a large broadband seismological network in and around Greenland, was initiated to monitor these events. Japan, a partner country of the GLISN project, has been sending a field team to Greenland each year since 2011, when a joint USA and Japanese team first established a dual seismic-GPS station (station code: ICESG-GLS2) on the Greenland ice sheet. In 2012, the same team contributed to the maintenance of ICESG-GLS2, as well as two other stations (NUUK and DY2G-GLS1). The quality of the long-period seismic waveform data obtained by these stations has been checked by comparing the data with global synthetic seismograms. Results indicate that the data from the three stations have not been substantially affected by noise, and that the quality is well controlled

Antarctica - A Key To Global Change

The most exciting initiative in the polar region was the International Polar Year (IPY) in 2007-2008, conducted as the 50th anniversary of the International Geophysical Year (1957-1958). The initiative greatly enhanced the exchange of ideas across nations and scientific disciplines to unveil the status and changes of planet Earth. This sort of interdisciplinary exchange helps us to understand and address grand challenges, such as rapid environmental change and its impact on society. In this regard, this book aims to compile the achievements of projects related to the IPY and post-IPY era, focusing especially on surface environmental variations associated with climate change, such as global warming